For example, an angular velocity sensor of this type has been disclosed in Japanese Patent Unexamined Publication No. 11-101644.
FIGS. 9 and 10 show the conventional angular velocity sensor disclosed in Japanese Patent Unexamined Publication No. 11-101644. FIG. 9 is a perspective view of an oscillator of the angular velocity sensor, and FIG. 10 is a side view of the same.
Referring to FIGS. 9 and 10, piezoelectric bodies 102, 103, and 104 having electrodes formed on both sides thereof are formed on oscillating body 101 in the form of an equilateral triangular pole made of elinvar or the like, the piezoelectric bodies serving as driving portions for driving bending oscillation. Piezoelectric bodies 105 and 106 having electrodes formed on both sides thereof are provided on the side of oscillating body 101 which is opposite to piezoelectric bodies 103 and 104 with reference to the center of the oscillating body in the longitudinal direction thereof, the piezoelectric bodies serving as detecting portions for detecting a change in bending oscillation when an angular velocity Ω is applied about the longitudinal axis of oscillating body 101. Piezoelectric bodies 105 and 106 are formed with the electrodes on both sides thereof as pseudo Coriolis force generating portions for causing bending oscillation of oscillating body 101 in the same direction as a Coriolis force which acts when the angular velocity Ω is applied about the longitudinal axis of oscillating body 101.
In the conventional angular velocity sensor, there has been a need for providing special piezoelectric bodies 105 and 106 on oscillating body 101 for the diagnosis of any failure of the detecting potions separately from piezoelectric body 102 as a driving portion and piezoelectric bodies 103 and 104 as detecting portions.